Apparatus for indicating the direction whence sound travels.



T. G. & W. HODGKINSON. APPARATUS FOR INDIGATING THE DIRECTION WHENOESOUND TRAVELS.

APPLIOATION FILED JULY 31, 1911.

Patented 0ct.7,1913.

4 SHEETS-SHEET 1.

In men hrs wq T. G. & w. HODGKINSON. APPARATUS FOR INDIGATING THEDIRECTION WHENGE SOUND TRAVELS.

APPLIUATION FILED JULY 31, 1911.

Patented Oct. 7, 1913.

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T. G. & W. HODGKINSON. APPARATUS FOR INDIGATING THE DIRECTION WHBNCEscum) TRAVELS. APPLICATION FILED JULY 31, 1911.

1 975 103. 7 Patented 0013.7, 1913.

4 SHEETS-SHEET 8.

[7L rez fars T. G. & W. HODGKINSON. APPARATUS FOR INDIGATING THEDIRECTION WHENGE SOUND TRAVELS.

APPLICATION FILED JULYBI, 1911.

1,075,1 O3, Patented Oct. 7, 1913.

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T IEFFTQFL THOMAS GERALn HoDGKINsoN, or occurs: or cnns'rna, ENGLAND,AND WILLIAM 1 HODGKI'NSON, or CALCUTTA, INDIA.

APPARATUS FOR INDICATING THE DIRECTION WHENCE SOUND- TRAVELS.

Specification of Letters Patent.

Patented Oct. 7, 1913.

Application filed July 31, 1911. Serial No. 641,515..

To all whom, it may concern Be it known. that we, THoMAs GERALDHoncmNsoN and WILLIAM HODGKINSON, subjects. of the King of England,residing in Cheshire, England, and Calcutta, India, respectively, haveinvented certain new and useful Improvements Apparatus for Indicatingthe Direction Whence Sound Travels, of which the following is aspecification.

This invention isfor improvements in or relating toapparatus forindicating the direction whence sound travels and is applicable to anypurpose requiring such information but will be described moreparticularly in. the form applied. to. ships for the purpose of one shipascertaining the direction of another ship. which can. be heard but notseen, or for detecting the direction of a fog-signal from a buoy orlighthouse.

According to this invention, for indicating the direction whence soundtravels or has traveled, receiving apparatus. is employed. operated bysound waves transmitted through the air. Preferably one or morereceiving devices arranged to pick up the sound waves from any directionare used in conjunction with indicator mechanism operating to show thedirection whence the sound waves picked up by the receivingdevicestravel or have traveled. Each receiver is conveniently of the microphonetype, that is to say, it comprises members that are in electricalcontact with each other and can be vibrated by the sound waves so that.the resistance between them is varied.

In a convenient form. ofapparatus a series of receivers are used whereofeach is screened fromsound waves in all directions but one and each isdirected to a different point of the compass. With this form. ofapparatus indicator mechanism is employed whereby the particularreceiver operated and hence the direction whence the sound travels canbe ascertained. Thus the receivers may be set around a center common tovthem all and screened providing each with a horn, the horns beingradially disposed to the center about which the receivers are set. Each.horn thus serves as a collector for sound traveling directly toward itsmouth, but it operates as a screen against the reception of sound wavesthat are not directed to. its month.

In the accompanying drawings :Figure l is a diagrammatic View of oneunit of the apparatus; Fig. 2 is an elevation of part of the apparatusindicated in Fig. 1; Fig. 3 is an elevation in. part section of the hornand receiver apparatus; Fig. 4 is a rear view of one of the receiversFig. 5 is a section through the same; Fig. 6 shows diagrammatically partof the indicator apparatus; Fig. 7, is a section through part ot thesame.

Like letters indicate like parts throughout the drawings.

The apparatus indicated in Fig. 1 constitutes. one complete unit, aseries of which is employed in the form of apparatus de scribed withreference to Figs. 1-6. but the single unit will first be brieflydescribed to enable the general arrangement to. be grasped. The receiver(which as stated above is of the microphone type) comprises a glassdiaphragm A having secured toit a flexible metallic tongue A A secondthin flexible metallic tongue A is carried at one end by a part that isadjustable rela-- tivcly to the diaphragm and the other end is made tobear lightly upon the tongue A at the center of the diaphragm. A batteryB has-one pole connected by wires 13 B to a differentially wound relayG. From the coils of the relay to which the wire B is connected, a wireB extends to the tongue A The tongue A is connected by a return wire B"connected by a bus-bar BF and wire B to the opposite pole of the batteryB.

i The battery B is further connected by wires C C that extend from thewire B to the I second winding of the difi'erential relay 0 and fromthis second winding a wire C is carriedto. an adjustable resistance 0*.The other end 01": the resistance is connected to the bus-bar B and thushas electrical connection through the wire B with the opposite poleofthe battery. A wire D further connects the busbar B? and the frame ofthe relay, while a wire D connects an insulated contact D? on the relayframe with one end of an electro-magnet coil D The other end oii thecoil is connected by a wire D to the wire C and thence through the wireB? to. the battery. The electro-magnet controls a.. catch or detent Ethat controls an indica-' tor plate E which always tends to rotate inthe direction of the arrow.

In using this apparatus the resistance C is adjusted tobalance theresistance of the contact tongues A A of the receiver so that. thearmature c of the relay, which is controlled by a spring 0 normallyremains in the position shown in Fig. 2. Directly the diaphragm A,however, is vibrated the resistance between the tongues A A is increasedso that the balance of the currents passing through the coils of therelay is disturbed. The armature 0 will therefore be drawn down by theaction of the relay coils and brought against the contact piece Dthereby establishing a circuit between the battery and theelectro-magnet D This causes the magnet D to lift the c'atchE andpermits the indicator disk E to turn around the movement of theindicator disk thus shows that the diaphragm has been made to vibrateand all that is necessary to adapt the apparatus for indicating thedirection whence the sound travels whereby the diaphragm is vibrated, isto screen the diaphragm on all sides but one. It will then be known thatthe sound travels from a point opposite the open side. Such a unit couldbe used by itself the receiver being turned around until the indicatorshowed it was receiving the sound waves, when the direction whence theytraveled would be known by the position of the receiver.

The screening is effected by mounting each diaphragm inside a horn F,Fig. 3. The

horns of the various receivers are arranged radially around a verticalaxis :0 w, the mouth of each horn being outward. They are carried in anyconveneint form of frame F and their inner ends are closed. Convenientlythe central portion of the frame is hollow as at 15 so that the wiresconnected to the various receivers can be carried down through the samethrough insulated plugs in the horns. The space F between the horns ispacked with any suitable material that is calculated to preventvibration of the horns themselves.

The particular construction of the receivers is shown in Figs. 4 and 5.The glass diaphragm A is mounted in a recessed annular plate A and heldin place by packing A that is gripped between the plate A and openfronted cover plate A The rear plate'A has a central orifice A so thatair is not confined between it and the diaphragm. The plate A is rigidlysecured to a yoke G which in turn is fastened to a heavy ring G Withinthe horn and near its far endare two internal flanges F, F and betweenthese the ring G is mounted, suitable packing G being introduced :toabsorb vibration between the horn and receiver.

The tongue A is shellacked or otherwise secured to the diaphragm A butthe tongue A is carried by an arm H that has an enlarged end 1-1. Thisend is provided with two recesses H entered by finely pointed set-screwsH carried by the annular plate is a spring E A A bridge piece H carriedby the plate A extends over the enlarged end 1-1 of the arm and at itscenter has a finely pointed set-screw H which enters a recess H in theend of the arm. The arm is thus carried between two set-screws on oneside and a centrally situated screw on the other side whose points areall brought to a line about which the arm is free to swing. The oppositeend of the arm is connected to the plate A by a difierential screw H anda spring H prevents any movement of the arm due to back lash. It will beseen that this device provides a fine adjustment for the tongue A sothat the latter can be made to bear exceedingly lightly against theoperating tongue A on the diaphragm. This insures delicacy of action andthe adjustable resistances O cooperate toward the same end as eachresistance can be tuned up to its.

particular receiver until a proper balance of the currents through therespective circuits is obtained. It follows that the slightestdisturbance of this resistance by the vibration of the diaphragm willcause the relay armature to be displaced thereby releasing the indicatoralloted to that particular receiver.

The detailed construction of the indicator mechanism is shown in Figs. 6and 7. As already. stated, each comprises an electromagnet D andindicator wheel or disk E, and a locking'pawl or catch E The pawl E isconveniently held down in such position as to lock the wheel E by aspring E Each indicator wheel or disk has a single tooth E that isengaged by the pawl E The disk is mounted free on a spindle E pivoted inplates E, E. Fast on the spindle is a wheel E and surrounding thespindle One end of'the spring bears against a pin E in the spindle andthe other bears against a collar E which in turn has frictionalengagement with the disk E. The wheel E' meshes with a wheel E that isconstantly rotated by any convenient mechanism. I

The various electro-magnets with their wheels are arranged in a circlearound the wheel E so that the one wheel meshes with all the wheels EThe plates E E are circular, the magnets being mounted on the outer edgeand covered in by an annular plate E which overlaps the plate E. In theplate E is a series of apertures E one opposite each indicator wheel Eand these lie in a circle just around the inner indicator mechanism hasbeen operated. It

will be seen that so long-as the wheels E are held stationary, the wheelE and wheels E merely rotatethe spindles E carrying with them thesprings E and washers or collars E which latter rub against thestationary wheels E. As soon however as one catch E is lifted theparticular wheel E locked by that catch will begin to travel by thefriction of the ro tating collar E against it. All that now is necessaryto locate the direction whence the sound operating the mechanismproceeds, is to establish the direction in which the receiver connectedwith each indicator faces. Thus if the apparatus is used on board shipthe top indicator ma be con-' nected to the receiver that faces Straightahead and the bottom one to that which faces direct Astern, the othersbeing allotted to the receivers allotted to the various points on theport and starboard sides. 1

It will be noted that this indicator mechanism is simple in constructionand requires no setting as directly any particular receiver ceases tooperate, the locking pawl E is brought back by its spring E to thelocking position and the indicating member will thus be automaticallybrought to rest in the non-indicating position.

Obviously the indicating members shown as wheels or perforated diskswhose arms are colored may take the form of solid disks if desired ormay have any other suitable shape.

The constructions of apparatus given above are only by way of example,as ob- 4 viously many modifications may-be made in the method ofcarrying out this invention without departing from the spirit of theinvention, for example, it might be possible in some instances to use asingle receiver with its diaphragm set in a horizontal plane and havingabove it a rotatable horn bent at a right angle so that the horn couldbe turned to receive the sound waves traveling in a horizontal planefrom any direction. The horn could be connected to a simple form ofindicator or it could be used itself to indicate the direction whencethe sound was traveling, and a galvanometer or other device employed toindicate when 1 the diaphragm was vibrating under the action of soundwaves collected by the horn.

What we claim as our invention and de sire to secure by Letters Patentis 1. In apparatus for determining the direction whence sound comes, thecombination with a vibratory diaphragm of two vibratory electricalcontact members normally in contact whereof one vibrates with thediaphragm and the other is resiliently supported in relation thereto soas to be set in vibra tion thereby, two electricalcircuits adapted toproduce opposed but normally balanced effects upon a part exposed to theaction of both and whereof one circuit includes the contact between thesaid two vibratory contact members, and means controlled by theapparatus for ascertaining the point toward which the apparatus isdirected when the diaphragm is vibrated, substantially as set forth.

2. In apparatus for determining the direction whence sound comes, thecombination with a plurality of vibratory diaphragms each provided withtwo vibratory electrical contact members normally in contact whereof onevibrates with the diaphragm and the other is resiliently supported inrelation thereto so as to be set in vibration thereby and means wherebyeach diaphragm is arranged to be excited by sound waves coming from onedirection only, of a plurality of movable indicator members, a drivingmember operatively connected with all the indicator members and that isconstantly moved when the apparatus is in use, means for holding eachindicator member normally stationary such means being 0perativclyconnected with a part exposed to the action of both of two electricalcircuits adapted to exert thereon opposed but normally balanced effectsand of which one circuit includes the contact between the said twovibratory contact members in such a manner that when the contact isvibrated the indicator member is released and permitted to move underthe action of the sin-' gle driving member, substantially as set forth.

3. In apparatus for determining th direction whence sound comes, thecombination, with a plurality of vibratory diaphragms each provided witha pair of vibratory electrical contact members normally in contactwhereof one vibrates with the diaphragm and the other is resilientlysupported in relation thereto so as to be set in vibration thereby andmeans whereby each diaphragm is arranged to be' excited by sound waves.coming from onedirection only, of a plurality of movable indicatormembers, a driving member that has frictional engagement with all theindicator members and is constantly moving when the apparatus is in use,a plurality of detents one for each indicator member that normally holdthe, indicator members stationary, and'operative connection between eachdetent and a part exposed to the action of both of two electricalcircuits adapted to' it's indicator member and permits the latter to bemoved by the driving member, substantially as set forth.

4. In apparatus for determining the direction whence sound comes, thecombination of, a vibratory glass'diaphragm, an electrical contactwhereof one element is carried by the glass diaphragm and vibratestherewith and the other takes .the form of a resilient tongue whose endis opposed to the first element, a part exposed to the action of both oftwo electrical circuits adapted to'exert thereon opposed but normallybalanced efiects and of which one circuit includes the contact betweenthe said two vibratory contact members and means controlled by theapparatus for ascertainingthe point toward which the apparatus isdirected when the diaphragm is vibrated substantially as set forth.

5. In apparatus for determining the direction whence sound comes, thecombination of, a vibratory glass diaphragm, an electrical contactwhereof one element is carried by the glass diaphragm and vibratestherewith and the other takes the form of a resilient tongue whose endis opposed to the first element, an arm to carry the resilient tonguethat is pivoted about an axis parallel to the plane wherein thediaphragm lies, a differential screw operative between the arm and itssupport, a part exposed to the action of both of two electrical circuitsada ted to exert thereon opposed. but normally balanced effects and ofwhich one circuit includes the contact between the said two vibratorycontact members and means controlled by the apparatus for ascertainingthe point toward which the apparatusis which line is parallel with thelane wherev in the diaphragm lies, two 0 the points being on one side ofthe arm and one on the other side in a position intermediate of theother two points, a differential screw operative between the arm and itssupport, a part exposed to the action of both of two electrical circuitsadapted to exert thereon opposed but normally balanced effects and ofwhich one circuit includes the contact between the said two vibratorycontact members, and means controlled by the apparatus for ascertainingthe point toward which the apparatus is directed when the diaphragm isvibrated substantially as set forth.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

THOMAS GERALD HODGKINSON, WILLIAM HODGKINSON. .Witnesses to T. G.Hodgkinson:

A. M. HAYWARD, HARRY B. BRIDGE. 'Witnesses to W. Hodgkinson:

CHARLES BL PERRY, K. .M. KIRKPATRICK.

